Article

Investigations of the role of cavitation in low-frequency sonophoresis using acoustic spectroscopy.

Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
Journal of Pharmaceutical Sciences (Impact Factor: 3.13). 03/2002; 91(2):444-53. DOI: 10.1002/jps.10024
Source: PubMed

ABSTRACT Application of low-frequency ultrasound significantly enhances skin permeability. The enhancement of skin permeability is mediated by cavitation, oscillation, and collapse of gaseous cavities. In this article, we report detailed investigations of the occurrence of cavitation during low-frequency sonophoresis. Cavitation was monitored by recording pressure amplitudes of subharmonic emission and broadband noise at four different ultrasound frequencies in the range of 20-100 kHz and at various intensities in the range of 0-2.6 W/cm(2). Enhancement of skin conductivity, in the presence of sodium lauryl sulfate (SLS), was also measured under the same ultrasound conditions. Enhancement of skin conductivity correlated well with the amplitude of broadband noise, which suggests the role of transient cavitation in low-frequency sonophoresis. No correlation was found between the subharmonic pressure amplitude and conductivity enhancement.

0 Bookmarks
 · 
197 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Transdermal drug delivery (TDD) has several significant advantages compared to oral drug delivery, including elimination of pain and sustained drug release. However, the use of TDD is limited by low skin permeability due to the stratum corneum (SC), the outermost layer of the skin. Sonophoresis is a technique that temporarily increases skin permeability such that various medications can be delivered noninvasively. For the past several decades, various studies of sonophoresis in TDD have been performed focusing on parameter optimization, delivery mechanism, transport pathway, or delivery of several drug categories including hydrophilic and high molecular weight compounds. Based on these various studies, several possible mechanisms of sonophoresis have been suggested. For example, cavitation is believed to be the predominant mechanism responsible for drug delivery in sonophoresis. This review presents details of various studies on sonophoresis including the latest trends, delivery of various therapeutic drugs, sonophoresis pathways and mechanisms, and outlook of future studies.
    Ultrasonics 07/2013; · 2.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Passive cavitation images (PCIs) generated from scattered acoustic waves are a potential technique for monitoring lesion formation during high-intensity focused ultrasound (HIFU) thermal ablation. HIFU lesion prediction by PCIs was assessed in ex vivo bovine liver samples (N = 14) during 30-s sonications with 1.1-MHz continuous-wave ultrasound (1989 W/cm(2) estimated spatial-peak intensity). Treated samples were sectioned, optically scanned, and the HIFU lesions segmented based on tissue discoloration. During each insonation, a 192-element, 7-MHz linear array (L7/Iris 2, Ardent Sound) passively recorded emissions from a plane containing the HIFU propagation axis oriented parallel to the image azimuth direction. PCIs were formed from beamformed A-lines filtered into fundamental, harmonic, ultraharmonic, and inharmonic frequency bands. Lesion prediction was tested using binary classification of local tissue ablation based on thresholded PCIs, with spatial specificity and sensitivity of lesion prediction quantified by the area under receiver operating characteristic curves (AUROC). Tadpole-shaped lesions were best predicted by harmonic emissions (AUROC = 0.76), prefocal lesions were best predicted by harmonic or ultraharmonic emissions (AUROC = 0.86), and cigar-type focal lesions were best predicted by fundamental and harmonic emissions (AUROC = 0.65). These results demonstrate spatial specificity and sensitivity when predicting HIFU lesions with PCIs. [Work supported in part by NIH grants F32HL104916 and R21EB008483.].
    The Journal of the Acoustical Society of America 05/2013; 133(5):3263. · 1.65 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Transdermal drug delivery offers an attractive alternative to the conventional drug delivery methods of oral administration and injections. However, the stratum corneum serves as a barrier that limits the penetration of substances to the skin. Application of ultrasound (US) irradiation to the skin increases its permeability (sonophoresis) and enables the delivery of various substances into and through the skin. This review presents the main findings in the field of sonophoresis in transdermal drug delivery as well as transdermal monitoring and the mathematical models associated with this field. Particular attention is paid to the proposed enhancement mechanisms and future trends in the fields of cutaneous vaccination and gene therapy.
    Advanced drug delivery reviews 01/2014; · 11.96 Impact Factor

Full-text

View
0 Downloads
Available from